New bionic ear uses smart plastic

The bionic ear technology, which coaxes nerve cells to regrow, may also one day help to repair damaged spinal cords (Image: iStockphoto)

Scientists are building a new bionic ear coated in a smart plastic that boosts the growth of nerve cells in the inner ear when it's zapped with electricity.

The technology, which also has potential for healing spinal cord injuries, is being developed at the Australian Centre for Medical Bionics and Hearing Science, part of Melbourne's Bionic Ear Institute.

Collaborator, Professor Gordon Wallace of the Intelligent Polymer Research Institute at the University of Wollongong, says the polymer polypyrrole is unusual because unlike most plastics, it can conduct electricity.

It can also act as a host structure for the molecules that stimulate nerve regrowth, known as neurotrophins.

Passing a small electric current through the plastic releases the molecules and helps to reverse the death and degeneration of hearing cells that occurs after prolonged deafness.

"We can encompass these molecules in the polymer structure," Wallace says.

"We inject small amounts of electricity into the structure and that causes the release of the molecules and makes them available to the nerve cells.

"The polymer controls the timing of release, and where the molecules are released, to maximise interaction with nerve cells."

The device would be powered by a small battery.

Wallace says the cell regrowth will create a better connection between the brain and the device, improving hearing when there's a noisy background and making listening to music easier.

Other applications of polypyrrole including batteries, biosensors, artificial muscles and generating solar energy, he says.

Encouraging cells to grow back

Wallace says his team has already demonstrated in the lab that it's possible to incorporate a particular neurotrophin, NT3, into the polymer and stimulate its release.